verilator/test_regress/t/t_gen_for.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain.
// SPDX-FileCopyrightText: 2003 Wilson Snyder
// SPDX-License-Identifier: CC0-1.0

module t (
    input clk
);

  integer cyc = 0;

  reg [7:0] crc;
  genvar g;

  wire [7:0] out_p1;
  wire [15:0] out_p2;
  wire [7:0] out_p3;
  wire [7:0] out_p4;

  // verilog_format: off
  paramed #(.WIDTH(8),  .MODE(0)) p1 (.in(crc), .out(out_p1));
  paramed #(.WIDTH(16), .MODE(1)) p2 (.in({crc,crc}), .out(out_p2));
  paramed #(.WIDTH(8),  .MODE(2)) p3 (.in(crc), .out(out_p3));
  gencase #(.MODE(3))             p4 (.in(crc), .out(out_p4));

  wire [7:0]   out_ef;
  enflop  #(.WIDTH(8))            enf (.a(crc), .q(out_ef), .oe_e1(1'b1), .clk(clk));
  // verilog_format: on

  always @(posedge clk) begin
    //$write("[%0t] cyc==%0d crc=%b %x %x %x %x %x\n", $time, cyc, crc, out_p1, out_p2, out_p3, out_p4, out_ef);
    cyc <= cyc + 1;
    crc <= {crc[6:0], ~^{crc[7], crc[5], crc[4], crc[3]}};
    if (cyc == 0) begin
      // Setup
      crc <= 8'hed;
    end
    else if (cyc == 1) begin
    end
    else if (cyc == 3) begin
      if (out_p1 !== 8'h2d) $stop;
      if (out_p2 !== 16'h2d2d) $stop;
      if (out_p3 !== 8'h78) $stop;
      if (out_p4 !== 8'h44) $stop;
      if (out_ef !== 8'hda) $stop;
    end
    else if (cyc == 9) begin
      $write("*-* All Finished *-*\n");
      $finish;
    end
  end

endmodule

module gencase (  /*AUTOARG*/
    // Outputs
    out,
    // Inputs
    in
);
  parameter MODE = 0;
  input [7:0] in;
  output [7:0] out;
  generate  // : genblk1
    begin
      case (MODE)
        2:
        mbuf mc[7:0] (
            .q(out[7:0]),
            .a({in[5:0], in[7:6]})
        );
        default:
        mbuf mc[7:0] (
            .q(out[7:0]),
            .a({in[3:0], in[3:0]})
        );
      endcase
    end
  endgenerate

endmodule

module paramed (  /*AUTOARG*/
    // Outputs
    out,
    // Inputs
    in
);
  parameter WIDTH = 1;
  parameter MODE = 0;
  input [WIDTH-1:0] in;
  output [WIDTH-1:0] out;

  generate
    if (MODE == 0) initial $write("Mode=0\n");
    // No else
  endgenerate

`ifndef NC  // for(genvar) unsupported
`ifndef ATSIM  // for(genvar) unsupported
  generate
    // Empty loop body, local genvar
    for (genvar j = 0; j < 3; j = j + 1) begin
    end
    // Ditto to make sure j has new scope
    for (genvar j = 0; j < 5; j = j + 1) begin
    end
  endgenerate
`endif
`endif

  generate
  endgenerate

  genvar i;
  generate
    if (MODE == 0) begin
      // Flip bitorder, direct assign method
      for (i = 0; i < WIDTH; i = i + 1) begin
        assign out[i] = in[WIDTH-i-1];
      end
    end
    else if (MODE == 1) begin
      // Flip using instantiation
      for (i = 0; i < WIDTH; i = i + 1) begin
        integer from = WIDTH - i - 1;
        if (i == 0) begin  // Test if's within a for
          mbuf m0 (
              .q(out[i]),
              .a(in[from])
          );
        end
        else begin
          mbuf ma (
              .q(out[i]),
              .a(in[from])
          );
        end
      end
    end
    else begin
      for (i = 0; i < WIDTH; i = i + 1) begin
        mbuf ma (
            .q(out[i]),
            .a(in[i^1])
        );
      end
    end
  endgenerate

endmodule

module mbuf (
    input a,
    output q
);
  assign q = a;
endmodule

module enflop (
    clk,
    oe_e1,
    a,
    q
);
  parameter WIDTH = 1;

  input clk;
  input oe_e1;
  input [WIDTH-1:0] a;
  output [WIDTH-1:0] q;

  reg [WIDTH-1:0] oe_r;
  reg [WIDTH-1:0] q_r;
  genvar i;

  generate
    for (i = 0; i < WIDTH; i = i + 1) begin : datapath_bits
      enflop_one enflop_one (
          .clk(clk),
          .d(a[i]),
          .q_r(q_r[i])
      );

      always @(posedge clk) oe_r[i] <= oe_e1;

      assign q[i] = oe_r[i] ? q_r[i] : 1'bx;
    end
  endgenerate
endmodule

module enflop_one (
    input clk,
    input d,
    output reg q_r
);
  always @(posedge clk) q_r <= d;
endmodule